The Baby Brezza AirSwirl Waterless Bottle Warmer is the most advanced way to safely and evenly warm baby bottles, using the same waterless technology used by nurses in hospitals! It warms with only hot air – not water – so there’s no bacteria or scale build-up inside and bottles are 100% dry when finished. The AirSwirl safely warms breastmilk without overheating, protecting nutrients, unlike traditional warmers that use steam heat which ruins breastmilk. The machine gently rocks the bottle during waterless warming to ensure even warming without hot spots or air bubbles. It warms so evenly and precisely, there is only 1° F temperature difference between the top and bottom of the milk during the waterless warming process, while other warmers create 21° F temperature difference in bottles. Choose your precise waterless warming time based on # ounces, milk type and bottle material. It's easy to use the Gentle Tap-Touch buttons to select your settings – just lightly tap, no need to press! The waterless warming time counts down on the LCD display, then the warmer beeps and automatically shuts off when finished. Works with most brands and types of bottles (excluding bottom vented bottles). Includes two rings that hold narrow neck and wide neck bottles.